There are known variously substituted 2-(pyridylmethylsulfinyl)-1H-benzimidazole derivatives and structurally related sulfoxides, that inhibit the proton pump and show anti-ulcer activity and the like. For example, a compound having a general name lansoprazole, 2-[[[3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridyl]methyl]sulfinyl]-1H-benzimidazole, and a salt thereof are reported in JP-A-61-50978 and the like. In addition, a compound having a general name, omeprazole (5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridyl)-methyl]sulfinyl]-1H-benzimidazole) and a salt thereof are described in JP-A-54-141783 and the like, a compound having a general name, pantoprazole (5-difluoromethoxy-2-[[(3,4-dimethoxy-2-pyridyl)-methyl]sulfinyl]-1H-benzimidazole) and a salt thereof are described in JP-A-61-22079 and the like, a compound having a general name, rabeprazole (2-[[[4-(3-methoxypropoxy)-3-methyl-2-pyridyl]methyl]sulfinyl]-1H-benzimidazole) and a salt thereof are described in JP-A-1-6270 and the like, and a compound having a general name, tenatoprazole (5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]sulfinyl]imidazo[4,5-b]pyridine) and a salt thereof are described in JP-A-63-146882 and the like.
However, since the above-mentioned compounds are unstable to acids, for oral administration, they are formulated into an enteric-coated preparation, filled in a capsule and administered, or filled in an enteric capsule and administered, or formulated into an enteric tablet and administered, thereby to prevent decomposition by gastric acid.
Therefore, the development of a prodrug of the above-mentioned compound, which is stable to acid and which resists decomposition by gastric acid, has been desired, and such prodrug has been reported in U.S. Pat. No. 6,093,734. In addition, prodrugs of proton pump inhibitors other than the above-mentioned prodrug have been disclosed in U.S. Pat. Nos. 4,045,563, 4,686,230, 4,873,337, 4,965,269, 5,021,433, 5,039,806 and the like.
In view of the above situation, the development of a prodrug of a proton pump inhibitor having superior stability to acid has been desired.
It is therefore an object of the present invention to provide a compound having superior stability to acid, which is converted to a proton pump inhibitor in living organisms and shows an anti-ulcer activity and the like, an intermediate therefor, a production method thereof and use thereof.